IT28G Integrated Toolcarrier and 924G, 924GZ and 928G Wheel Loaders Transmission Caterpillar

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Sudden movement of the machine or release of oil under pressure can cause injury to persons on or near the machine. To prevent possible injury, perform the procedure that follows before testing and adjusting the power train.

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Personal injury can result from hydraulic oil pressure and hot oil. Hydraulic oil pressure can remain in the hydraulic system after the engine has been stopped. Serious injury can be caused if this pressure is not released before any service is done on the hydraulic system. Make sure all of the attachments have been lowered, oil is cool before removing any components or lines. Remove the oil filler cap only when the engine is stopped, and the filler cap is cool enough to touch with your bare hand.

Problem List

Note: Many of the following problems can create diagnostic codes or event codes in ET. These codes can help find the root cause of the problem. ET should be used to retrieve the logged codes and active codes.

1. The transmission does not operate in any gear.

2. The transmission slips in all gears.

3. The transmission gets hot.

4. The pump noise is not normal.

5. Noise in the transmission is not normal.

6. The transmission operates in FORWARD only.

7. The transmission operates in REVERSE and fourth gear FORWARD only.

8. The transmission operates in REVERSE and first through third gear FORWARD only.

9. The transmission does not operate in first gear, FORWARD or REVERSE.

10. The transmission does not operate in second gear, FORWARD or REVERSE.

11. The transmission does not operate in third gear, FORWARD or REVERSE and fourth gear FORWARD.

12. The clutch engagement is slow for all gears.

13. The clutch engagement is slow for all FORWARD gears or all REVERSE gears or the clutch engagement is slow for any one gear in both FORWARD and in REVERSE.

14. The transmission stays engaged when the neutralizer is actuated.

15. The transmission engages but the machine does not move.

16. While the engine is running and the parking brake is engaged, the alarm does not sound when the transmission selection lever is put into either a FORWARD or a REVERSE direction.

17. The backup alarm will not sound when the selection lever is put into REVERSE.

18. There is low lubrication pressure.

19. There is high lubrication pressure.

20. The transmission will not shift automatically.

Probable Causes

Problem 1

The transmission does not operate in any gear.

Probable Causes

1. The fuse for the transmission shifter is open or the fuse for the transmission shifter is blown.

2. There is a problem in the electrical circuit. Check ET for active diagnostic codes.

3. There is low system voltage.

4. The transmission shift control unit is faulty.

5. There is low oil pressure.

6. The torque converter has failed.

7. There is mechanical failure in the transmission.

8. The clutch discs and plates are worn too much.

9. The brake pressure sensor is inoperative.

10. The parking brake is engaged.

11. The Machine Security System is active.

12. The transmission direction and speed control lever and the transmission direction control switch are both in FORWARD or REVERSE.

Problem 2

The transmission slips in all of the gears.

Probable Causes

1. There is low oil pressure.

2. The torque converter has failed.

3. There is mechanical failure in the transmission.

4. The clutch discs and plates are worn too much.

Problem 3

The transmission gets hot.

Probable Causes

1. There is a low coolant level in the engine radiator.

2. There is too much slippage by the torque converter that is caused by too much load.

3. The transmission gear is incorrect for the load on the machine. Shift to a lower gear.

4. The temperature gauge is faulty.

5. The oil level is incorrect.

6. The oil cooler or lines are restricted.

7. The clutch slips too much. This could be caused by low oil pressure or by damaged clutches.

8. Low oil flow is caused by pump wear or leakage in the hydraulic system.

9. The oil is mixed with air.

10. The torque converter inlet relief valve is stuck open and causes low oil flow through the torque converter.

11. The clutch or clutches are not fully releasing. This can be caused by warped plates or discs. This can also be caused by a broken return spring or a weak return spring.

Problem 4

The pump noise is not normal.

Probable Causes

1. A loud sound for short time periods of time indicates that foreign material is in the transmission hydraulic system.

2. A constant loud noise indicates pump failure.

3. There is air at the inlet side of the pump.

Problem 5

There is noise in the transmission that is not normal.

Probable Causes

1. There are damaged gears in the transmission.

2. There are worn teeth on the clutch plates or on the clutch discs.

3. There is slipping clutch plates and there is noise from the disc.

4. There are other parts that are worn or there are other parts that are damaged.

Problem 6

The transmission operates in FORWARD only.

Probable Causes

1. The solenoid for clutch 3 (reverse) is inoperative.

2. There is a problem in the electrical circuit.

3. Clutch 3 is not engaged because of discs and plates that have too much wear.

4. Clutch 3 is not engaged because of low oil pressure due to leaking seals on the piston or the shaft.

5. Clutch 3 is not engaged because of broken components.

6. The modulating valve for clutch 3 is stuck.

Problem 7

The transmission operates in REVERSE and fourth gear FORWARD only.

Probable Causes

1. The solenoid for clutch 1 (forward low) is inoperative.

2. There are problems in the electrical circuit.

3. Clutch 1 is not engaged because of low oil pressure. The low oil pressure is due to seals that leak on the piston or on the shaft.

4. Clutch 1 is not engaged because discs and plates have too much wear.

5. Clutch 1 is not engaged because of broken components.

6. The modulating valve for clutch 1 is stuck.

Problem 8

The transmission operates in REVERSE and first through third gear FORWARD only.

Probable Causes

1. The solenoid for clutch 2 (forward high) is inoperative.

2. There are problems in the electrical circuit.

3. Clutch 2 is not engaged because of low oil pressure due to seals that leak on the piston or on the shaft.

4. Clutch 2 is not engaged because discs and plates have too much wear.

5. Clutch 2 is not engaged because of broken components.

6. The modulating valve for clutch 2 is stuck.

Problem 9

The transmission does not operate in first gear FORWARD or REVERSE.

Probable Causes

1. The solenoid for clutch 6 (first speed) is inoperative.

2. There is a problem in the electrical circuit.

3. Clutch 6 is not engaged because of low oil pressure due to seals that leak on the piston or on the shaft.

4. Clutch 6 is not engaged because discs and plates have too much wear.

5. Clutch 6 is not engaged because of broken components.

6. The modulating valve for clutch 6 is stuck.

Problem 10

The transmission does not operate in second gear FORWARD or REVERSE.

Probable Causes

1. The solenoid for clutch 4 (second speed) is inoperative.

2. There is a problem in the electrical circuit.

3. Clutch 4 is not engaged because of low oil pressure due to seals that leak on the piston or on the shaft.

4. Clutch 4 is not engaged because discs and plates have too much wear.

5. Clutch 4 is not engaged because of broken components.

6. The modulating valve for clutch 4 is stuck.

Problem 11

The transmission does not operate in third gear FORWARD or REVERSE and the transmission does not operate in fourth gear FORWARD.

Probable Causes

1. The solenoid for clutch 5 (third speed and fourth speed) is inoperative.

2. There is a problem in the electrical circuit.

3. Clutch 5 is not engaged because of low oil pressure due to seals that leak on the piston or on the shaft.

4. Clutch 5 is not engaged because discs and plates have too much wear.

5. The modulating valve for Clutch 5 is stuck.

Problem 12

Clutch engagement is slow for all gears.

Probable Causes

1. There is low oil pressure.

2. The transmission relief valve is stuck or the transmission relief valve needs adjustment.

Problem 13

The clutch engagement is slow for all FORWARD gears or all REVERSE gears or the clutch engagement is slow for any one gear in both FORWARD and REVERSE.

Probable Causes

1. The low clutch pressure is because of seals that leak on the piston or on the shaft for the affected gear.

2. A modulating valve is stuck.

3. There is an electrical fault.

Problem 14

The transmission stays engaged when the brake pedal is pushed.

Probable Causes

1. The brake pressure sensor is not functioning properly.

2. There is a failure in the transmission neutralizer override switch.

Problem 15

The transmission engages but the machine does not move.

Probable Causes

1. The machine brakes are locked up.

2. The parking brake is not released or the parking brake is locked up.

3. There is a mechanical failure in a differential.

4. There is a mechanical failure in a final drive.

5. There is a mechanical failure in the transmission.

Problem 16

While the engine is running and the parking brake is engaged, the alarm does not sound when the transmission selection lever is put into either a FORWARD or REVERSE direction.

Probable Causes

1. There is a failure of the alarm.

2. There is a failure of the wiring.

Problem 17

The backup alarm will not sound when the selection lever is put in REVERSE.

Probable Causes

1. There is a failure of the backup alarm fuse.

2. There is failure of the backup alarm.

3. There is failure of the wiring.

4. There is a problem with the transmission control lever.

Problem 18

There is low lubrication pressure.

Probable Causes

1. The converter inlet relief valve is passing flow.

2. There is low pump flow or pressure.

Problem 19

High lubrication pressure

Probable Causes

1. There are blocked lube holes in the clutch shaft.

Problem 20

The transmission will not shift automatically.

Probable Causes

1. The autoshift switch is in the OFF.

2. The autoshift switch is not operating correctly.